1. Field of the Invention
The present invention relates to a valve for metering fluid, the umbrella term “fluid” referring to a flowing medium, for both gases and liquids in accordance with fluid dynamics.
2. Description of the Related Art
In a known, so-called outward-opening injector (Published European patent application document EP 2 366 888 A1), the valve housing has a hollow cylindrical nozzle body including a valve seat surrounding the nozzle opening situated at one end, a housing pot with the nozzle body protruding centrally through its pot bottom into the housing pot and a housing cap which seals the housing pot and has a cap jacket and cap bottom, an inlet connection for the fluid being situated in the cap jacket. Inside the housing pot, a solenoid coil of an electromagnet sits on the nozzle body. A ring plate made of a nonmagnetic material is connected to the magnet pot and the nozzle body in a fluid-tight manner in each case and, together with the pot bottom of the housing pot, encloses an encapsulated coil space in which the solenoid coil is situated and, together with the housing cap, encloses a fluid-filled valve space into which the nozzle body protrudes. A valve needle is guided axially displaceably in the nozzle body and carries a closing head cooperating with the valve seat on one end. There is an annular clearance between the valve needle and the cylinder wall of the nozzle body through which the fluid flows from the valve space to the metering opening. A magnet armature of the electromagnet attached to the valve needle delimits a working air gap of the electromagnet with the end face of the nozzle body protruding out of the coil space. A valve-closing spring designed as a disk spring is supported between the magnet armature and the ring plate, exerting on the magnet armature a force which applies the closing head to the valve seat via the valve needle. A folded or corrugated bellows arrangement, having a folded or corrugated bellows tightly connected to the valve needle and the cap bottom and having a calibration spring situated in the folded or corrugated bellows, extends between the end of the valve needle remote from the closing head and the cap bottom of the housing cap in the valve space. The calibration spring is supported on the needle end of the valve needle on the one hand and on an axially adjustable adjusting bolt in the cap bottom on the other hand. The calibration spring may be prestressed in the desired way by displacement of the adjusting bolt and acts upon the valve needle with a compressive force acting in the valve opening direction. The diameter of the valve seat and the hydraulic diameter of the folded or corrugated bellows are the same, so that the valve needle is pressure equalized for all fluid pressures, and the dynamic response of the valve is independent of the fluid pressure.